Section 4. County Officers

(a) Any county may elect a chief executive officer as provided by law. He shall have those duties and powers provided by law and those provided by county ordinance.
(b) The President of the Cook County Board shall be elected from the County at large and shall be the chief executive officer of the County. If authorized by county ordinance, a person seeking election as President of the Cook County Board may also seek election as a member of the Board.
(c) Each county shall elect a sheriff, county clerk and treasurer and may elect or appoint a coroner, recorder, assessor, auditor and such other officers as provided by law or by county ordinance. Except as changed pursuant to this Section, elected county officers shall be elected for terms of four years at general elections as provided by law. Any office may be created or eliminated and the terms of office and manner of selection changed by county-wide referendum. Offices other than sheriff, county clerk and treasurer may be eliminated and the terms of office and manner of selection changed by law. Offices other than sheriff, county clerk, treasurer, coroner, recorder, assessor and auditor may be eliminated and the terms of office and manner of selection changed by county ordinance.
(d) County officers shall have those duties, powers and functions provided by law and those provided by county ordinance. County officers shall have the duties, powers or functions derived from common law or historical precedent unless altered by law or county ordinance.
(e) The county treasurer or the person designated to perform his functions may act as treasurer of any unit of local government and any school district in his county when requested by any such unit or school district and shall so act when required to do so by law.